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| 型号： | MAX1518BETJ+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 23/25页 |
| 文件大小： | 0K |
| 描述： | IC DC-DC CONV TFT-LCD 32-TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 60 |
| 应用： | 转换器，TFT，LCD |
| 输入电压： | 2.6 V ~ 6.5 V |
| 输出数： | 1 |
| 输出电压： | 2.6 V ~ 13 V |
| 工作温度： | -40°C ~ 100°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 32-WFQFN 裸露焊盘 |
| 供应商设备封装： | 32-TQFN-EP（5x5） |
| 包装： | 管件 |
TFT-LCD DC-DC Converter with
Operational Amplifiers
Applications Information
Power Dissipation
An IC’s maximum power dissipation depends on the
thermal resistance from the die to the ambient environ-
ment and the ambient temperature. The thermal resis-
tance depends on the IC package, PC board copper
area, other thermal mass, and airflow.
The MAX1518B, with its exposed backside pad sol-
dered to 1in 2 of PC board copper, can dissipate
approximately 1.7W into +70 ° C still air. More PC board
copper, cooler ambient air, and more airflow increase
the possible dissipation, while less copper or warmer
air decreases the IC’s dissipation capability. The major
components of power dissipation are the power dissi-
pated in the step-up regulator and the power dissipat-
ed by the operational amplifiers.
Step-Up Regulator
The largest portions of power dissipation in the step-up
regulator are the internal MOSFET, the inductor, and the
output diode. If the step-up regulator has 90% efficiency,
approximately 3% to 5% of the power is lost in the internal
MOSFET, approximately 3% to 4% in the inductor, and
approximately 1% in the output diode. The remaining 1%
to 3% is distributed among the input and output capacitors
and the PC board traces. If the input power is about 5W,
the power lost in the internal MOSFET is approximately
150mW to 250mW.
Operational Amplifier
The power dissipated in the operational amplifiers
depends on their output current, the output voltage,
and the supply voltage:
PD SOURCE = I OUT _( SOURCE ) × ( V SUP ? V OUT _ )
PD SINK = I OUT _( SINK ) × V OUT _
where I OUT_(SOURCE) is the output current sourced by
the operational amplifier, and I OUT_(SINK) is the output
current that the operational amplifier sinks.
In a typical case where the supply voltage is 13V and
the output voltage is 6V with an output source current
of 30mA, the power dissipated is 180mW.
PC Board Layout and Grounding
Careful PC board layout is important for proper opera-
tion. Use the following guidelines for good PC board
layout:
? Minimize the area of high-current loops by placing
the inductor, the output diode, and the output
capacitors near the input capacitors and near the
LX and PGND pins. The high-current input loop
goes from the positive terminal of the input capacitor
to the inductor, to the IC’s LX pin, out of PGND, and
to the input capacitor’s negative terminal. The high-
current output loop is from the positive terminal of
the input capacitor to the inductor, to the output
diode (D1), and to the positive terminal of the output
capacitors, reconnecting between the output capac-
itor and input capacitor ground terminals. Connect
these loop components with short, wide connec-
tions. Avoid using vias in the high-current paths. If
vias are unavoidable, use many vias in parallel to
reduce resistance and inductance.
? Create a power-ground island (PGND) consisting of
the input and output capacitor grounds, PGND pin,
and any charge-pump components. Connect all of
these together with short, wide traces or a small
ground plane. Maximizing the width of the power-
ground traces improves efficiency and reduces out-
put voltage ripple and noise spikes. Create an
analog ground plane (AGND) consisting of the
AGND pin, all the feedback-divider ground connec-
tions, the operational-amplifier divider ground con-
nections, the COMP and DEL capacitor ground
connections, and the device’s exposed backside
pad. Connect the AGND and PGND islands by con-
necting the PGND pin directly to the exposed back-
side pad. Make no other connections between these
separate ground planes.
? Place all feedback voltage-divider resistors as close
to their respective feedback pins as possible. The
divider’s center trace should be kept short. Placing
the resistors far away causes their FB traces to
become antennas that can pick up switching noise.
Take care to avoid running any feedback trace near
LX or the switching nodes in the charge pumps.
? Place the IN pin and REF pin bypass capacitors as
close to the device as possible. The ground connec-
tion of the IN bypass capacitor should be connected
directly to the AGND pin with a wide trace.
? Minimize the length and maximize the width of the
traces between the output capacitors and the load
for best transient responses.
? Minimize the size of the LX node while keeping it
wide and short. Keep the LX node away from feed-
back nodes (FB, FBP, and FBN) and analog ground.
Use DC traces to shield if necessary.
Refer to the MAX1518B evaluation kit for an example of
proper PC board layout.
Chip Information
TRANSISTOR COUNT: 4608
______________________________________________________________________________________
23
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1518BETJ+ | 功能描述:LCD 驱动器 TFT-LCD DC-DC Conv w/Op Amps RoHS:否 制造商:Maxim Integrated 数位数量:4.5 片段数量:30 最大时钟频率:19 KHz 工作电源电压:3 V to 3.6 V 最大工作温度:+ 85 C 最小工作温度:- 20 C 封装 / 箱体:PDIP-40 封装:Tube |
| MAX1518BETJ+T | 功能描述:LCD 驱动器 TFT-LCD DC-DC Conv w/Op Amps RoHS:否 制造商:Maxim Integrated 数位数量:4.5 片段数量:30 最大时钟频率:19 KHz 工作电源电压:3 V to 3.6 V 最大工作温度:+ 85 C 最小工作温度:- 20 C 封装 / 箱体:PDIP-40 封装:Tube |
| MAX1518ETJ | 功能描述:LCD 驱动器 RoHS:否 制造商:Maxim Integrated 数位数量:4.5 片段数量:30 最大时钟频率:19 KHz 工作电源电压:3 V to 3.6 V 最大工作温度:+ 85 C 最小工作温度:- 20 C 封装 / 箱体:PDIP-40 封装:Tube |
| MAX1518ETJ+ | 功能描述:LCD 驱动器 TFT-LCD DC-DC Conv w/Op Amps RoHS:否 制造商:Maxim Integrated 数位数量:4.5 片段数量:30 最大时钟频率:19 KHz 工作电源电压:3 V to 3.6 V 最大工作温度:+ 85 C 最小工作温度:- 20 C 封装 / 箱体:PDIP-40 封装:Tube |
| MAX1518ETJ+T | 功能描述:LCD 驱动器 TFT-LCD DC-DC Conv w/Op Amps RoHS:否 制造商:Maxim Integrated 数位数量:4.5 片段数量:30 最大时钟频率:19 KHz 工作电源电压:3 V to 3.6 V 最大工作温度:+ 85 C 最小工作温度:- 20 C 封装 / 箱体:PDIP-40 封装:Tube |
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